SUV4-20: SUV4-20 subfamily methylates H4K20 in other species. Human, mouse, and Xenopus laevis have two SUV4-20 members, while in Drosophila and several other insects there is only one member. In silkworm, we identified only one SUV4-20 member like other insects. Phylogenetic analysis of SUV4-20 subfamily suggests that BmSuv4-20 clusters with Suv4-20 proteins of Drosophila, Anopheles gambiae, and other insects . Besides, SUV4-20 proteins of vertebrates cluster together. Among vertebrates, Suv4-20h2 (Suv4-20 homolog 2) of human and Rattus norvegicus are shorter than Suv4-20h1 (Suv4-20 homolog 1) and cluster together. BmSuv4-20 has the same domain structure as SUV4-20 proteins of other species that there is only one domain the SET located on the N-terminal of them20. (1)